JP2938710B2 - Fe-Cr alloy with excellent workability and high-temperature strength - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an Fe--Cr alloy having excellent workability and high-temperature strength. The present invention also relates to F which is excellent in acid resistance and / or oxidation resistance in addition to workability and high temperature strength.
It relates to an e-Cr alloy.

[0002]

2. Description of the Related Art Generally, Fe-Cr alloys are known as materials having excellent corrosion resistance, but various improvements in the physical properties of Fe-Cr alloys, including improvements in corrosion resistance and workability, have been proposed as exemplified below. ing.

[0003] Japanese Patent Publication No. 63-58904 discloses a ferritic stainless steel having a Cr content of 11.0 to 16.0% by weight. Suggests steel.

Japanese Patent Publication No. 64-6264 discloses a Fe—Cr alloy having a Cr content of 8.0 to 35.0% by weight,
A bright annealed stainless steel material which contains i, Mn and Nb in specific amounts and has excellent rust resistance has been proposed.

Japanese Patent Publication No. 2-1902 discloses an Fe—Cr alloy having a Cr content of more than 20.0% by weight and not more than 25% by weight, particularly high temperature resistance during welding in which Mo, Mn and Nb each contain a specific amount. A corrosion-resistant ferritic stainless steel with excellent crackability and weld toughness is proposed.

In Japanese Patent Application Laid-Open No. 61-186451, Cr is used.
Fe-Cr alloy with a content of 25-50% by weight, especially S
An alloy having a specific amount of i, Mn and Mo and excellent in sour resistance has been proposed.

Japanese Unexamined Patent Publication (Kokai) No. 62-267450 discloses a high-purity ferritic stainless steel having a Cr content of 16 to 19% by weight and containing particularly a specific amount of Mo and having excellent intergranular corrosion resistance. Has been proposed.

Japanese Patent Application Laid-Open No. 1-287253 discloses Fe-C having a Cr content of 15-26% by weight and an Al content of 4-6% by weight.
An Al-containing ferritic stainless steel which is an r-Al alloy and contains a rare earth element in a specific amount in a small amount and has excellent oxidation resistance and productivity is proposed.

JP-A-2-232344 discloses a Fe--Cr alloy having a Cr content of 25.0 to 30.0% by weight, which is particularly excellent in adhesion to components containing a specific amount of Mo and seawater resistance. Has proposed a ferritic stainless steel.

JP-A-3-2355 discloses that the Cr content is 1
A ferritic stainless steel having a cold workability, toughness, and corrosion resistance in which a specific amount of Nb is contained in a ratio of 6.0 to 25.0% by weight of Fe-Cr alloy, particularly in the ratio of the total amount of C and N. Suggests steel.

[0011]

These Fe-Cr alloys use a relatively large amount of Cr because corrosion resistance is first considered important. As a result, the ductility is reduced, the workability is not always sufficient, and it is difficult to finish into a desired shape according to the application. For example, when pipes are formed and subjected to bending and used for piping applications, troubles such as breakage during bending occur, and further improvement in workability has been desired.

Further, the strength at high temperatures is not sufficient, and for applications exposed to high temperatures, for example, exhaust pipes for automobile exhaust gas, further improvement in high-temperature strength and high-temperature fatigue properties has been desired. Further, there has been a demand for further improvement in use as a chemical industrial plant material which requires acid resistance.

That is, an object of the present invention is to provide an Fe-Cr alloy having improved workability and strength at high temperatures. Another object of the present invention is to provide an Fe-based alloy having excellent acid resistance and / or oxidation resistance in addition to workability and high-temperature strength.
It is to provide a Cr alloy.

[0014]

Means for Solving the Problems The present inventor has made intensive studies to achieve the above object, and as a result, surprisingly,
It has been found that a Fe-Cr alloy having extremely low impurity properties such as C, N, O, P, and S existing in the Cr alloy has remarkably excellent ductility.
It has been found that an alloy obtained by adding a specific amount of at least one selected from Ti, Nb, Zr, V, Ta, W and B to a Cr alloy has improved strength at high temperatures, and has completed the present invention. .

According to the present invention, the Cr content is 3 to 60% by weight, the total amount of C, N, O, P and S is 100 ppm or less, and selected from Ti, Nb, Zr, V, Ta, W and B. At least one of the following formula (1) is contained,
An Fe—Cr alloy excellent in workability and high-temperature strength characterized by the balance of Fe and unavoidable impurities is provided. 0.01% by weight ≦ Ti + Nb + Zr + V + Ta + W + 50B ≦ 6% by weight (1)

According to the present invention, the Cr content is 5-6.
0% by weight, the total amount of C, N, O, P and S is 100 pp
m, containing at least one selected from Ti, Nb, Zr, V, Ta, W and B in an amount satisfying the following formula (1), and further containing at least one selected from Ni, Co and Cu as follows: The present invention provides an Fe—Cr alloy having excellent workability, high-temperature strength, and acid resistance, characterized by being contained in an amount satisfying the formula (2) and the balance being Fe and unavoidable impurities. 0.01% by weight ≦ Ti + Nb + Zr + V + Ta + W + 50B ≦ 6% by weight (1) 0.01% by weight ≦ Ni + Co + 2Cu ≦ 6% by weight (2)

According to the present invention, the Cr content is 3-6.
0% by weight, the total amount of C, N, O, P and S is 100p
pm or less, containing at least one selected from Ti, Nb, Zr, V, Ta, W and B in an amount satisfying the following formula (1), and further containing at least one selected from Al, Si and Mn as follows: An amount satisfying the formula (3) and / or Ca, Mg
And at least one selected from rare earth elements (REM) in an amount satisfying the following formula (4), and is excellent in workability, high-temperature strength and oxidation resistance characterized by being composed of the balance of Fe and unavoidable impurities. An Fe-Cr alloy is provided. 0.01% by weight ≦ Ti + Nb + Zr + V + Ta + W + 50B ≦ 6% by weight (1) 0.1% by weight ≦ 3Al + 2Si + Mn ≦ 50% by weight (3) 0.001% by weight ≦ 4Ca + 4Mg + REM ≦ 0.2% by weight (4)

Further, the Cr content is 5 to 60% by weight,
The total amount of N, O, P and S is 100 ppm or less, T
at least one selected from i, Nb, Zr, V, Ta, W and B in an amount satisfying the following formula (1);
At least one selected from i, Co and Cu is contained in an amount satisfying the following formula (2).
And / or at least one selected from Ca, Mg and rare earth elements (REM) in an amount satisfying the following formula (3):
F, excellent in workability, high-temperature strength, acid resistance and oxidation resistance, characterized by the balance consisting of Fe and unavoidable impurities
An e-Cr alloy is provided. 0.01% by weight ≦ Ti + Nb + Zr + V + Ta + W + 50B ≦ 6% by weight (1) 0.01% by weight ≦ Ni + Co + 2Cu ≦ 6% by weight (2) 0.1% by weight ≦ 3Al + 2Si + Mn ≦ 50% by weight (3) 001% by weight ≦ 4Ca + 4Mg + REM ≦ 0.2% by weight (4)

[0019]

The present invention will be described below in more detail. (I) First, the F of the present invention which is excellent in workability and high-temperature strength
The e-Cr alloy will be described. Figure 1 shows Fe-18% C
FIG. 4 shows the total amount of C, N, O, P and S and the result of a tensile test at room temperature with respect to the r alloy, based on a conventional alloy having the total amount of about 500 ppm. It can be seen that when the content is 100 ppm or less as compared with the conventional alloy, the value of elongation is improved, the yield strength is significantly reduced, and the ductility is visibly improved. In FIG. 1, the change in elongation (%) and the change in proof stress (yield strength) (N / mm ² ) refer to C + N + O + S + P = 500 p for each alloy component.
It shows the difference in tensile properties from that of pm. The basic tensile properties are as follows. Fe-18Cr, C + N + O + S + P = 500 ppm, elongation 30%, yield strength 330 N / mm ² Fe-30Cr, C + N + O + S + P = 500 ppm, elongation 25%, yield strength 450 N / mm ²

FIG. 2 shows (Ti + Nb + Zr + V + Ta +
W + 50B) is a graph showing the relationship between the increase in value and the high temperature yield strength (900 ° C.), the increase in high-temperature strength when the above value is 0.01% by weight or more becomes 0.1 N / mm ² or more, a high temperature It is clear that the strength at the point is improved.

Next, the composition of the alloy of the present invention will be described. Cr: 3 to 60% by weight, preferably 5 to 45% by weight. If the above range, combined with other conditions of the present invention,
Although an alloy having excellent oxidation resistance is obtained, an excessive content exceeding 60% by weight is not preferable because the cost increases.

C, N, O, P, S; the total amount of these elements is 100 ppm or less, preferably 85 ppm or less. This improves the ductility of the alloy, that is, the workability, and at the same time, is excellent in oxidation resistance in combination with the condition of the Cr content specified above. When this amount exceeds 100 ppm, such excellent effects are not exhibited.

Ti, Nb, Zr, V, Ta, W and B, which contain at least one of these elements and whose contents are added so as to satisfy the following formula (1), preferably formula (1a). 0.01% by weight ≦ Ti + Nb + Zr + V + Ta + W + 50 × B ≦ 6% by weight (1) 0.1% by weight ≦ Ti + Nb + Zr + V + Ta + W + 50 × B ≦ 4% by weight (1a) Strength is improved. However, if these elements are excessively blended and deviate from the range of the formula (1), a problem that the brittleness of the material is promoted while maintaining the high-temperature strength occurs.
Further, the contents of Ti, Nb, Zr, V, Ta, W or B are preferably in the following ranges, respectively. Ti: Ti ≦ 5 (C% + N%) Nb: 0.01 to 1% by weight Zr: 0.01 to 1% by weight V: 0.02 to 1% by weight Ta: 0.01 to 1% by weight W: 0 0.03 to 1% by weight B: 0.0003 to 0.3% by weight

The alloy of the present invention which satisfies the above conditions is excellent in workability and high-temperature strength, and thus is suitable for uses such as pipes for automobile exhaust gas which involve pipe forming and subsequent bending.

Fe-Cr as described above for (I) of the present invention
To manufacture an alloy, first, ultrahigh-purity electrolytic iron and electrolytic Cr are used as raw materials. The main impurity of any of the raw materials is oxygen, and for removing oxygen, for example, 10 ^-5 torr.
The Fe—Cr alloy of the present invention can be manufactured by melting and casting under an ultra-high vacuum of r or more.

(II) Next, the Fe—Cr alloy of the present invention having excellent workability, high-temperature strength and acid resistance will be described.
FIG. 1 shows the total amount of C, N, O, P and S and the result of a tensile test at room temperature with respect to the Fe-18% Cr alloy, based on the conventional alloy having the total amount of about 500 ppm. . 100p content compared to conventional alloy
When it is less than pm, the elongation value is improved, the yield strength is significantly reduced, and the ductility is clearly improved.

FIG. 2 shows (Ti + Nb + Zr + V + Ta +
W + 50B) is a graph showing the relationship between the increase in value and the high temperature yield strength (900 ° C.), the increase in the high-temperature yield strength when the above value is 0.01% by weight or more becomes 0.1 N / mm ² or more, a high temperature It is clear that the strength at the point is improved.

FIG. 3 is a graph showing the relationship between the total amount of C, N, P, O and S and the degree of corrosion for the Fe-36% Cr-3.2% Co alloy, with the total amount being within 100 ppm. It is clear that the corrosion rate is extremely low.

FIG. 4 shows Fe-Cr-1.6% Ni-1.
FIG. 4 is a graph showing the relationship between the Cr content and the degree of corrosion for a 4% Co alloy when the total amount of C, N, O, P and S is 100 ppm or less and when it exceeds 100 ppm. From FIG. 2, C + N + O + P + S is 100 ppm.
It is clear that the following alloys have significantly lower corrosion rates than alloys exceeding 100 ppm, and the tendency is remarkable when the Cr content is 5% by weight or more.

FIG. 5 shows an Fe-38% Cr alloy (however, C
+ N + O + P + S = 62 ppm), Ni + Co
FIG. 4 is a diagram showing the relationship between + 2Cu and the degree of corrosion, where Ni + Co
It has been clarified that when the value of + 2Cu is 0.01% by weight or more, the degree of corrosion is reduced.

FIG. 6 shows Fe-46% Cr-3.0% Co.
-1.2% Cu alloy (however, C + N + O + P + S = 64
ppm), Ti + Nb + Zr + Ta + V + W + 5
It is a figure showing the relationship between the value of 0B (% by weight) and the degree of corrosion.
It is clear that when the above value is 0.01% by weight or more, the degree of corrosion is low.

Next, the composition of the alloy of the present invention will be described. Cr: 5 to 60% by weight, preferably 10 to 40% by weight. When the Cr content is within this range, an alloy having excellent acid resistance can be obtained as described in the section of [Action]. Excessive Cr content is undesirable because it causes a reduction in workability. Further, the effect of improving the acid resistance is saturated.

C, N, O, P, S: The total amount of these elements is 100 ppm or less, preferably 85 ppm or less. As described in the section of [Action], by being 100 ppm or less, excellent high-temperature strength combined with other conditions,
Shows acid resistance and excellent workability.

Ti, Nb, Zr, V, Ta, W and B, which contain one or more of these elements and are added so as to satisfy the following formula (1), preferably formula (1a). 0.01% by weight ≦ Ti + Nb + Zr + V + Ta + W + 50B ≦ 6% by weight (1) 0.1% by weight ≦ Ti + Nb + Zr + V + Ta + W + 50B ≦ 4% by weight (1a) The content at the above range improves the strength at high temperatures. However, if these elements are excessively blended and deviate from the range of the formula (1), the high temperature strength is maintained but the brittleness of the material is promoted. Also, Ti, Nb, Zr, V,
The content of Ta, W or B is preferably in the following range. Ti: Ti ≦ 5 (C wt% + N wt%) Nb: 0.01 to 1 wt% Zr: 0.01 to 1 wt% V: 0.02 to 1 wt% Ta: 0.01 to 1 wt% W : 0.03 to 1% by weight B: 0.0003 to 0.3% by weight

Cu, Ni, Co; All of these elements are important and useful elements having an effect of improving the acid resistance of the alloy. The alloy of the present invention contains one or more selected from these elements, and the amount is in a range that satisfies the following formula.

0.01% by weight ≦ Ni + Co + 2Cu ≦ 6% by weight (2) Preferably, 0.05% by weight ≦ Ni + Co + 2Cu ≦ 5.0% by weight (2a) The compounding amount of Ni, Co, and Cu is as described above. If it is less than the range, the corrosion resistance is poor, and if it is too large, the productivity of the alloy is poor.

The preferred contents of Ni, Co and Cu are as follows, for the same reasons as described above. Ni; 0.05 to 5.0% by weight Co; 0.05 to 5.0% by weight Cu; 0.05 to 2.5% by weight

The Fe—Cr alloy satisfying the above conditions is
It is excellent in workability and high-temperature strength, and has remarkably excellent properties in acid resistance.

The Fe—Cr alloy described in (II) of the present invention can be obtained by using, as raw materials, ultrahigh-purity electrolytic Fe, electrolytic Cr, electrolytic N
i, electrolytic Cu, electrolytic Co, iodide method Ti, electrolytic reduction N
b, molten salt electrolysis Zr, reduction V, electrolysis Ta, electrolysis reduction W,
It can be produced by using high-purity ferroboron or the like.

The main impurity in each content is oxygen. To remove this oxygen, the Fe-Cr of the present invention is melted and cast under an ultra-high vacuum exceeding 10 ^-5 torr, preferably more than 10 ^-7 torr. Alloys can be manufactured.

(III) Next, the Fe—Cr alloy of the present invention having excellent workability, high-temperature strength and oxidation resistance will be described.
FIG. 1 shows the total amount of C, N, O, P and S and the result of a tensile test at room temperature with respect to the Fe-18% Cr alloy, based on the conventional alloy having the total amount of about 500 ppm. . 100p content compared to conventional alloy
When it is less than pm, the elongation value is improved, the yield strength is significantly reduced, and the ductility is clearly improved.

FIG. 2 shows (Ti + Nb + Zr + V + Ta +
W + 50B) is a graph showing the relationship between the increase in value and the high temperature yield strength (900 ° C.), the increase in the high-temperature yield strength when the above value is 0.01% by weight or more becomes 0.1 N / mm ² or more, a high temperature It is clear that the strength at the point is improved.

FIG. 7 shows that the total amount of C + N + O + P + S is 10
Oxidation resistance test results for Fe-Cr alloys of 0 ppm or more and 100 ppm or less (1350 k in air, 12 hr
7 is a graph showing the weight loss after scale removal). The properties equal to or higher than those of a conventional stainless steel having a Cr content of 12% by weight or more are as follows: the total amount of C, N, O, P and S
When the content is 0 ppm or less, it is apparent that the Cr content is obtained at 3% by weight or more, and that the Cr content is reduced by high purification, thereby saving resources.

FIG. 8 is a graph showing the results of an oxidation resistance test (weight reduction after removing 1250 K and 12 hr scale in the air) of an Fe- (15 to 30)% Cr alloy.
When (3Al + 2Si + Mn) is 0.1% by weight or more, it is apparent that the oxidation resistance is excellent.

FIG. 9 is a graph showing the results of an oxidation resistance test (weight reduction after removing 1250 K and 12 hr scale in the air) of an Fe- (15 to 30)% Cr alloy.
When (4Ca + 4Mg + REM) is 0.001% by weight or more, it is apparent that the oxidation resistance is excellent.

Next, the composition and embodiment of the alloy of the present invention will be described. The Fe-Cr alloy of the present invention having excellent workability, high-temperature strength and oxidation resistance has the following three aspects, each of which will be described.

(1) First embodiment of the present invention: Cr: 3 to 60% by weight, preferably 5 to 45% by weight. If the above range, combined with other conditions of the present invention,
Although an alloy having excellent oxidation resistance is obtained, an excessive content exceeding 60% by weight is not preferable because the cost increases.

C, N, O, P, S; the total amount of these elements is 100 ppm or less, preferably 85 ppm or less. Thus, by reducing the content of these elements, the ductility of the alloy, that is, the workability is improved, and at the same time, the alloy is excellent in oxidation resistance in combination with the condition of the Cr content specified above. When this amount exceeds 100 ppm, such excellent effects are not exhibited.

Ti, Nb, Zr, V, Ta, W and B, which contain one or more of these elements and are added so as to satisfy the following formula (1), preferably formula (1a). 0.01% by weight ≦ Ti + Nb + Zr + V + Ta + W + 50B ≦ 6% by weight (1) 0.1% by weight ≦ Ti + Nb + Zr + V + Ta + W + 50B ≦ 4% by weight (1a) The content at the above range improves the strength at high temperatures. However, if these elements are excessively blended and deviate from the range of the formula (1), the high temperature strength is maintained but the brittleness of the material is promoted. Also, Ti, Nb, Zr, V,
The content of Ta, W or B is preferably in the following range. Ti: Ti ≦ 5 (C wt% + N wt%) Nb: 0.01 to 1 wt% Zr: 0.01 to 1 wt% V: 0.02 to 1 wt% Ta: 0.01 to 1 wt% W : 0.03 to 1% by weight B: 0.0003 to 0.3% by weight

Al, Si, Mn: One or more of these elements are contained, and the content is represented by the following formula (3), preferably (3)
a) is added so as to satisfy a). 0.1% by weight ≦ 3Al + 2Si + Mn ≦ 50% by weight (3) 0.3% by weight ≦ 3Al + 2Si + Mn ≦ 30% by weight (3a) By containing these elements in the above range, the oxidation resistance is remarkably improved. However, excessive addition of 3Al +
If the value of 2Si + Mn exceeds 50% by weight, the processability deteriorates, which is not preferable. The content of Al, Si or Mn is preferably within the following range. Al: 0.1 to 4% by weight Si: 0.3 to 3% by weight Mn: 0.5 to 10% by weight

(2) Second Embodiment of the Present Invention The preferred contents of Cr, C, N, O, P and S, and Ti, etc. described in the first embodiment apply to this embodiment. You. In the alloy of the second embodiment, one or more selected from Ca, Mg and REM are contained as follows.

Ca, Mg, REM: These elements are not essential components in the alloy of the present invention, but when they are contained so as to satisfy the following formula (4), the oxidation resistance is further improved, and a preferable result is obtained. Get. However, these elements are excessively contained (4Ca + 4Mg + RE
If the value of M) exceeds 0.2% by weight, surface defects of the alloy are likely to occur, which is not preferable. 0.001% by weight ≦ 4Ca + 4Mg + REM ≦ 0.2% by weight (4) The content of Ca, Mg or REM is preferably in the following range. Ca: 0.0002 to 0.03
Wt% Mg: 0.0003-0.03 wt% REM: 0.0005-0.15 wt%

The alloy of the present invention that satisfies the above conditions is excellent in workability, high-temperature strength and oxidation resistance, and thus is suitable for uses such as pipes for automobile exhaust gas.

In order to produce the Fe—Cr alloy of the present invention, first, ultrahigh-purity electrolytic iron and electrolytic Cr are used as raw materials. The main impurity of any of the raw materials is oxygen, and the Fe—Cr alloy of the present invention can be manufactured by melting and casting under an ultrahigh vacuum higher than 10 ⁻⁷ torr to remove this oxygen.

(3) Third Embodiment of the Invention An alloy that satisfies both the conditions of the alloy of the first embodiment and the conditions of the alloy of the second embodiment of the present invention described above, that is, the Cr content is 3 to 60% by weight, the total amount of C, N, O, P and S is 100 ppm or less.
one or more selected from i, Nb, Zr, V, Ta, W and B in an amount satisfying the above formula (1);
At least one selected from i, Mn, and Al is contained in an amount satisfying the formula (3), and at least one selected from Ca, Mg, and a rare earth element (REM) satisfies the formula (4). Fe-Cr alloys are also alloys having even better oxidation resistance and workability, and are preferably used in the above-mentioned applications.

The Fe of the present invention including these three embodiments
-To manufacture a Cr alloy, use ultra-high purity electrolytic iron, electrolytic chromium, zone melt silicon, molten salt electrolytic manganese, molten salt electrolytic aluminum, molten salt electrolytic calcium, electrolytic reduced magnesium, electrolytic reduced rare earth metal as raw materials . The main impurity of any of the raw materials is oxygen. To remove this oxygen, the Fe-Cr of the present invention is melted and cast under an ultra-high vacuum higher than 10 ^-5 torr.
Alloys can be manufactured.

(IV) Finally, in addition to workability and high-temperature strength,
The Fe—Cr alloy of the present invention having excellent acid resistance and oxidation resistance will be described. This alloy according to the present invention takes account of the alloy composition particularly excellent in acid resistance described in (II) and the alloy composition particularly excellent in oxidation resistance described in (III).
Therefore, only the embodiment will be described below, and the detailed description is omitted since it is as described in (II) and (III).

In the present invention, there are three embodiments similar to the invention of (III), wherein C + N + O + P ≦ 100 ppm,
5 to 60% by weight, 0.01% ≦ Ti + Nb + Zr
In addition to + V + W + 50B ≦ 6%, only the changing part will be described below for each mode. (1) First embodiment of the present invention One or more selected from Ni, Co and Cu are contained in an amount satisfying the following formula (2). 0.01% by weight ≦ Ni + Co + 2Cu ≦ 6% by weight (2) At least one selected from Si, Mn and Al is contained in an amount satisfying the following formula (3). 0.1% by weight ≦ 3Al + 2Si + Mn ≦ 50% by weight (3)

(2) Second embodiment of the present invention One or more selected from Ni, Co and Cu are contained in an amount satisfying the following formula (2). 0.01% by weight ≦ Ni + Co + 2Cu ≦ 6% by weight (2) At least one selected from Ca, Mg and rare earth elements (REM) is contained in an amount satisfying the following formula (4). 0.001% by weight ≦ 4Ca + 4Mg + REM ≦ 0.2% by weight (4)

(3) Third Embodiment of the Invention One or more selected from Ni, Co and Cu are contained in an amount satisfying the following formula (2). 0.01% by weight ≦ Ni + Co + 2Cu ≦ 6% by weight (2) At least one selected from Si, Mn and Al is contained in an amount satisfying the following formula (3). 0.1% by weight ≦ 3Al + 2Si + Mn ≦ 50% by weight (3) At least one selected from Ca, Mg and rare earth elements (REM) is contained in an amount satisfying the following formula (4). 0.001% by weight ≦ 4Ca + 4Mg + REM ≦ 0.2% by weight (4)

The method of manufacturing the alloy of the present invention is exactly the same as described above, and a detailed description thereof will be omitted.

[0062]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments. (Example 1) Corresponding to invention alloys 1 to 6, comparative alloys 1 to 6 ...
Corresponding to claim 1 An alloy having a composition shown in Table 1 was melted by ultra-high vacuum melting at 10 ^-5 Torr or more using ultrahigh-purity electrolytic iron and a high-purity metal material by an electrolytic method or the like.

This was heated to about 1200 ° C., finished by hot rolling to a thickness of about 5 mm, finally cold rolled to 1.0 to 2.0 ^t mm, and then recrystallized and adjusted for grain size. Annealing of 50
Applied at 0-1100 ° C.

From this, tensile test pieces at room temperature and high temperature were cut out and subjected to respective tests in accordance with JIS (the room temperature tensile test piece was JIS No. 5, and the high temperature tensile test was JIS.
G0567).

The oxidation test was conducted at 1350 k for 12 h on the sample of Table 1 in which a high purity metal was melted under high vacuum.
r Heated in an electric furnace in an air atmosphere, then air-cooled to room temperature, measured the weight loss when the scale on the specimen surface was removed, and used as an index of oxidation resistance. The results are shown in Table 2. Table 2
From the results, it is apparent that both the workability and the high-temperature strength are remarkably improved in the component range of the present invention as compared with the material in the component range of the comparative example.

(Example 2) Corresponding to invention alloys 7 to 12 and comparative alloys 7 to 9 Corresponding to claim 2 100 kg of a test material having the component range shown in Table 1 was placed in a high-frequency induction heating ultrahigh vacuum melting furnace. Produced. After subjecting these test materials to forging, cutting, and hot rolling, annealing and cold rolling were performed to produce a steel sheet having a thickness of 1.0 mm.

Thereafter, 1 mm ^t ×
A test piece of 50 mm × 50 mm was prepared and subjected to an immersion test in 5% HCl at 40 ° C. for 24 hours. An immersion test of 40% H ₂ SO ₄ at 50 ° C. for 24 hours was performed to determine the degree of corrosion (g / m ² · hr). It was measured. Table 2 summarizes the results. From the results in Table 2, it is clear that corrosion in the acid immersion test is significantly suppressed in the component range of the present invention as compared with the material in the component range of the comparative example.

From these results, it was found that the Fe—Cr system (5 ≦ C
r ≦ 60) alloy, the total content of C, N, O, P, and S is 100 ppm or less, and one or more of Ca, Ni, and Co is 0.01% by weight ≦ Co + Ni + 2Cu ≦
It is clear that an alloy having excellent acid resistance can be obtained by containing it in the range of 6% by weight.

Further, in addition to the above-mentioned components, Ti, Nb, Z
one or more of r, V, Ta, W, B,
01% by weight ≦ Ti + Nb + Zr + V + Ta + W + 50B
It is clear that an alloy having more excellent acid resistance can be obtained by containing ≦ 6.0% by weight.

(Example 3) Corresponding to invention alloys 13 to 26 and comparative alloys 10 to 12 Corresponding to claim 3 An alloy having the composition shown in Table 1 was prepared by using ultrahigh-purity electrolytic iron, electrolytic Cr and a high-purity metal material. It was melted by ultra-high vacuum melting at 10 ^-7 Torr or more.

This was heated to about 1200 ° C., finished by hot rolling to a thickness of about 5 mm, finally cold-rolled to 1.0 to 2.0 ^t mm, and then recrystallized and adjusted for grain size. Annealing of 50
Applied at 0-1100 ° C.

From this, tensile test specimens at room temperature and high temperature were cut out and subjected to respective tests in accordance with JIS (the room temperature tensile test specimen was JIS No. 5, and the high temperature tensile test was JIS.
Performed at 900 ° C. according to SG0567).

The oxidation test was performed at 1350k for 12 hours.
r, heated in an electric furnace in an air atmosphere, and then air-cooled to room temperature, and the weight loss when the scale on the test piece surface was removed was measured and used as an index of oxidation resistance. Table 2 shows the test results. From Table 2, it is clear that the oxidation resistance is greatly improved in the component range of the present invention as compared with the component range of the comparative example.

(Example 4) Inventive alloys 27 to 29 Corresponding to claim 4 The alloys having the compositions shown in Table 1 were over 10 ^-7 Torr by using ultrahigh-purity electrolytic iron, electrolytic Cr and high-purity metal materials. It was produced by high vacuum melting.

This was heated to about 1200 ° C., finished by hot rolling to a thickness of about 5 mm, finally cold rolled to 1.0 to 2.0 ^t mm, and then recrystallized and adjusted for the crystal grain size. Annealing of 50
Applied at 0-1100 ° C. 5% HCl, 40 ° C. corrosion degree, 4%
A 0% H ₂ SO ₄ , 50 ° C. corrosion rate, and 900 ° C. high temperature tensile test were performed and evaluated in the same manner. The results are shown in Table 2. It is clearly shown that those falling within the scope of the present invention exhibit excellent properties.

(Changes in Elongation and Yield Strength) With respect to the test materials obtained in all the above Examples, changes in elongation and changes in proof strength (yield strength) were examined. The change in elongation (%) and the change in proof stress (yield strength) (N / mm ² ) indicate the difference in tensile properties between each alloy component and C + N + O + S + P = 500 ppm. The basic tensile properties are as follows. Fe-18Cr, C + N + O + S + P = 500 ppm, elongation 30%, yield strength 330 N / mm ² Fe-30Cr, C + N + O + S + P = 500 ppm, elongation 25%, yield strength 450 N / mm ²

[0077]

[Table 1]

[0078]

[Table 2]

[0079]

[Table 3]

[0080]

[Table 4]

[0081]

[Table 5]

[0082]

[Table 6]

[0083]

[Table 7]

[0084]

[Table 8]

[0085]

[Table 9]

[0086]

[Table 10]

[0087]

The alloy of the present invention is excellent in workability, strength at high temperature, or in addition to these, is excellent in acid resistance and / or oxidation resistance, and thus is suitably used for applications such as pipes for automobile exhaust gas.

[Brief description of the drawings]

FIG. 1. C, N, and Fe-18% Cr alloys
It is a graph which shows the relationship between the total amount of O, P, and S and a tensile characteristic.

FIG. 2 is a graph showing a relationship between Ti + Nb + Zr + V + Ta + W + 50B and an increase in high-temperature yield strength.

FIG. 3 is a graph showing the relationship between the total amount of C, N, P, O, and S and the degree of corrosion.

FIG. 4 is a graph showing the relationship between the amount of Cr and the degree of corrosion.

FIG. 5 is a graph showing the relationship between Ni + Co + 2Cu and the degree of corrosion.

FIG. 6 is a graph showing the relationship between Ti + Nb + Zn + Ta + V + W + 50B and the degree of corrosion.

FIG. 7 is a graph showing the relationship between Cr content and weight loss after an oxidation resistance test.

FIG. 8 is a graph showing the relationship between (3Al + 2Si + Mn) and oxidation resistance.

FIG. 9 is a graph showing the relationship between (4Ca + 4Mg + REM) and oxidation resistance.

──────────────────────────────────────────────────の Continuation of the front page (72) Inventor Yoshihiro Yazawa 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Engineering Co., Ltd. (72) Inventor Yasushi Kato Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba No. 1 in Kawasaki Steel Engineering Co., Ltd. (72) Inventor Tetsu Owada 1 in Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Co., Ltd. Technical Research Headquarters (56) References JP-A-57-134542 (JP, A JP, A 53-2328 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C22C 27/00-38/52

Claims (4)

(57) [Claims] (1) A Cr content of 3 to 60% by weight, C, N, O,
The total amount of P and S is 100 ppm or less, and Ti, N
Excellent in workability and high-temperature strength characterized by containing at least one selected from b, Zr, V, Ta, W and B in an amount satisfying the following formula (1), the balance being Fe and unavoidable impurities. Fe-Cr alloy. 0.01% by weight ≦ Ti + Nb + Zr + V + Ta + W + 50B ≦ 6% by weight (1) 2. The method according to claim 1, wherein the Cr content is 5 to 60% by weight, and C, N, O,
Total amount of P and S is 100 ppm or less, Ti, Nb, Z
At least one selected from the group consisting of r, V, Ta, W and B is contained in an amount satisfying the following formula (1).
and at least one selected from the group consisting of Fe and Fe, which is excellent in workability, high-temperature strength and acid resistance, characterized by being composed of the balance of Fe and unavoidable impurities.
Cr alloy. 0.01% by weight ≦ Ti + Nb + Zr + V + Ta + W + 50B ≦ 6% by weight (1) 0.01% by weight ≦ Ni + Co + 2Cu ≦ 6% by weight (2) 3. The method according to claim 1, wherein the Cr content is 3 to 60% by weight, and C, N, O,
The total amount of P and S is 100 ppm or less, Ti, Nb,
At least one selected from Zr, V, Ta, W and B is contained in an amount satisfying the following formula (1), and one or more selected from Al, Si and Mn is also contained in an amount satisfying the following formula (3). And / or Ca, Mg and rare earth elements (RE
M) containing at least one selected from M) in an amount satisfying the following formula (4), the balance being Fe and unavoidable impurities, characterized by excellent workability, high-temperature strength and oxidation resistance.
e-Cr alloy. 0.01% by weight ≦ Ti + Nb + Zr + V + Ta + W + 50B ≦ 6% by weight (1) 0.1% by weight ≦ 3Al + 2Si + Mn ≦ 50% by weight (3) 0.001% by weight ≦ 4Ca + 4Mg + REM ≦ 0.2% by weight (4) 4. The method according to claim 1, wherein the Cr content is 5 to 60% by weight, and C, N, O,
The total amount of P and S is 100 ppm or less, Ti, Nb,
At least one selected from Zr, V, Ta, W and B is contained in an amount satisfying the following formula (1), and at least one selected from Ni, Co and Cu is satisfied in an amount satisfying the following formula (2). An amount of at least one selected from Al, Si and Mn satisfying the following formula (3) and / or
1 selected from a, Mg and rare earth elements (REM)
A Fe—Cr alloy excellent in workability, high-temperature strength, acid resistance and oxidation resistance, characterized in that the Fe-Cr alloy contains at least the seeds in an amount satisfying the following formula (4) and the balance is Fe and inevitable impurities. 0.01% by weight ≦ Ti + Nb + Zr + V + Ta + W + 50B ≦ 6% by weight (1) 0.01% by weight ≦ Ni + Co + 2Cu ≦ 6% by weight (2) 0.1% by weight ≦ 3Al + 2Si + Mn ≦ 50% by weight (3) 001% by weight ≦ 4Ca + 4Mg + REM ≦ 0.2% by weight (4)